Figure 2.—

Inversion types and the generation of aneuploid chromosomes. (A) Four types of inversion (right) are possible, depending upon the structure of the parental chromosome carrying the RS elements in cis (left). For clarity, we show the reduced forms of the elements (RSr). (B) Recombination between pairs of inversions produces aneuploid chromosomes. For illustration, we show the products of an exchange between a type 1 and a type 2 inversion, a w duplication (the parental line is w⁺) and a deletion carrying two copies of w⁺. Since the nonrecombinant progeny carry only a single copy of w⁺, the deletion may be identifiable by virtue of a darker eye color.